Updated load_cert to use the proper key identifier

```
/*
 * Copyright (c) 2010 Raytheon BBN Technologies.
 *
 * PERMISSION
 *
 * This material is based upon work supported by the Defense Advanced
 * Research Projects Agency and Space and Naval Warfare Systems
 * Center, Pacific, under Contract No. N66001-09-C-2073.
 * Approved for Public Release, Distribution Unlimited
 */
```
I missed a change in my last pull request to update the load_cert function to also use the 0x9E key instead of the 0x9B key.  According to the SP800-73-3 Table 6, Part 1 the container ID for the 0x9E key is still 0x0500 so I just needed to update the key reference identifier.